BY V.BHANU CHANDER TIRUPATI, INDIA
Pi line Pipe li : Transportation of liquids and gases from one place to another place place..
Pipe line activity : ¾ Survey ¾ Unloading & stocking of pipes at site ¾ Marking ¾ Trench excavation ¾ Blasting contd…
¾ Sand bedding ¾ Pipe Pi lowering l i ¾ Laying, joining ¾ Back filling ¾ Sand encasing ¾ Specials S i l fixing fi i contd…
¾ Pedestals, thrust blocks & valve chambers ¾ Hydro testing ¾ Commissioning i i i ¾ Final measurement ¾ Reconciliation
TYPE OF PIPES
Mild steel (MS)
Glass reinforcement plastic (GRP)
Ductile iron (DI) ( )
Cast iron (CI)
High density poly ethylene (HDPE)
Poly vinyl chloride (PVC) Contd… Contd
Pre stressed concrete (PSC)
Reinforcement cement concrete (RCC)
Asbestos cement pressure (AC)
Bar wrapped pp steel cylinder y ((BWSC))
Galvanized iron (GI)
Low alloy pipe (LA)
HDPE pipe i
RCC pipe i
DI pipe i
Obtain work permit before starting excavation work.
Marking is to be made
Excavate trench up to required level with free working
The side slopes of cutting shall generally have the following slopes for stability. slope 1:1 1:2
for excavation in clay, muram & boulders etc hard muram
NOTE: Slope not required for soft & hard rock
TRANSPORTATION OF MATERIAL TO SITE
Pipes shall be transported to the site of laying and stacked along the route
Padding shall be placed between coated pipes and timber to avoid damage to the coating
Suitable gap during pipe stacking should be left at proper intervals to permit access from one side to the other
Unloading & stocking of material : Each pipe & special should be properly stacked at site in such a manner so as not to distort their circularity or cause any damage to their outer coating.
manual pipe handling : B f Before h dli the handling th pipe, i work men should wear helmet and gloves 1.
Ropes p used to lift the material must be in ggood condition,, and it should not be let over sharp edges
Ensure that the persons are moved away from the pit while placing the pipe (if it is heavy)
while handling materials in the wet season, ensure that the materials are free from slush as it may cause slipping.
Pipe handling by machinery ¾
Slings should be in good condition and free from defects,
Ensure proper clamping of slings, these are provided on same direction on free length g
Ensure pproper p visibilityy for the crane.
C.I & D.I PIPES LOWERING, LAYING &JOINING
Pipes should be lowered slowly in to the trench by means of chain ppulleyy block and tripod p stand or cranes or with the help of ropes. Rubber gaskets shall be inserted into the groove in the socket. Spigot end shall be lubricated with good quality of grease or oil, then the spigot shall be slipped into socket by means of jack on the other end. end p g ends of all ppipes p shall face upp stream irrespective p of Spigot the direction of water flow.
GRP PIPES LOWERING, LAYING AND JOINING
Lowering and laying : Pipe Pi shall h ll be b laid l id in i dry d condition diti andd under d no circumstances i t they shall rest on sludgy bedding. Pipes shall rest continuously on the bottom of the trench.
Clearance of approximately 100mm in depth and width equal to length l h off the h collar ll plus l 30mm 30 on both b h sides id shall h ll be b provided at the joint which shall be refilled from sides after the jjoint is made.
The pipe should be lowered in to the trenches either by pulley or by means of two ropes. For road crossing or river crossing the pipe shall laid 2.0mtr. Below the bed level. The pipe should be encased with 300mm thick sand.
Joining : 1. Spigot and socket and socket joint with double water tight rubber bb ring i gasket k t packing ki p g jjoint with water tight g rubber ringg 2. Double socket coupling gasket packing 3. Flanged joint is used for connecting the valves, the flanged joint is made from the same materials as the pipe 4. End pipes should not kept open, the ends shall be covered up either by suitable cap or plug or double layer of gunny bags.
GRP joint with Spigot & socket end
M.S PIPES LOWERING, LAYING, JOINING & PAINTING
Before Laying, M.S pipes should be coated with cement or Painting 1.
surface cleaning : The pipe should be cleaned before painting with special epoxy thinner. This avoids oil, Greece marks on the pipe. Due to these marks the paint wasn't sticking. Inside dust can be removed by using compressed air. air
primary coating After surface cleaning, first primer coating is necessary. For this purpose zinc phosphate primer is combined with activator in 6:1 ratio. Zinc phosphate primer is component a & activator i i component b, is b so primer = component a + component
Out side coating : After primary coating, out side of pipe painted with epoxy coall tar which hi h is i combined bi d with i h activator i i 4:1 in 41 ratio.
Inside : Foodd grade d epoxy usedd for f inside i id painting i i resists i corrosion, this is the combination of resin & cure in 1:1 ratio.
Lowering, laying and joining of MS pipes:
¾ Before welding the pipe faces shall be cleaned by scraping by wire brushes ¾ MS pipe provided with cement mortar / apoxy painting in lining and coating ¾ The Th ends d off MS pipes i shall h ll have h beveled b l d ends d for f welding ldi
While assembling, assembling the pipes shall be close to uniform gap. gap (Gap depends up on thickness) electrodes shall be conform to is 814 814--1991 i.e, ee--6013
¾ MS pipes are manufactured either by electro resistance weldingg or submerged g arc weldingg pprocess longitudinally g y or spirally welded ¾ Manual metal arc welding with covered electrodes. electrodes
What is metal arc welding In metal arc welding a metal rod is used as one electrode during the welding operation this metal electrode is melted by the heat of the arc and is fused with the base metal. Welding defects : 1. Lack of penetration, 2. Slag inclusion, 3. Under cut, 4 Poor 4. P ffusion, i 5. Porosity, 6 Weld crack, 6. crack 7. Spatter, pp g & distortion. 8. Wrapping
HDPE PIPE LAYING & JOINING
Fusion welding is commonly used in HDPE and is a permanent type of joint The pipes shall be brushed through out to remove any soil deposited or stone their in Pipes shall be laid in dry condition and under no circumstances theyy shall rest on slushyy beddingg Clearance of required depth & width on both sides shall be provided, provided at the joint which shall be refilled from sides after the joint is made
¾ For road crossing or river crossing the pipe shall be laid 2 meter below the bed level and encasing should be done ¾ Pipe after transporting to the exact place should be cut square by the hacksaw blade ¾ The face of the ppipe p should be slightly g y scrapped pp pprior to the fusion welding to remove oxidized layer ¾ Ensure the leveling of pipes is maintained at the time of fusion welding
¾ The heating mirror / pan should be heated up to 200 deg. deg. c and the surface of the pan should be 210 + or – 5 deg deg.. C ¾ The heating pan should be metallic plate which is heated up to the required temperature either by electrical coil embedded inside or by blow torch ¾ The fusion welding of pipe should be held in either side of the heating mirror / pan with Teflon paper on each side ¾ The contact pressure of 0.2 kg/cm kg/cm2 2 in either side if the pipe should be maintained
¾ Initial heating time for achieving the molten rim, varies from 1 to 5 min depending on the pipe wall thick & size. size. ¾ Pipes should be removed from the heating mirror / pan, when the rim of the molten material is formed and ensure that the rim formation is not excessive. excessive. ¾ Immediate joint should be made by the application of moderate pressure of approx. approx. 1 to 2 kg/cm kg/cm2 2 for 2 to 3 sec sec.. ¾ while joining, the pressure should be maintained until the joint is luke warm warm.. ¾ After the pressure is relieved, the joint should be allowed to cool completely
Back Filling : Back fill with excavated soil should be free from cinders, i d ashes, h slag, l refuse, f rubbish, bbi h vegetable t bl or organic i metal, lumpy or frozen metal, boulders rocks, other materials which in the opinion of any authority, is deleterious. deleterious. Concrete slabs over pipes : when pipes are laid below roads (which may be subjected to heavy traffic loads), trenches should be covered with ith reinforced i f d concrete t slabs l b
GRP Lamination Details Materials used in the process: 1. Grinding wheels, (machine) 2. Surface, 3. Robin, 4. Matt,, 5. Resin, 6. Hardener, 7 Aerosol powder, 7. powder
L i ti Process Lamination P : 1. First,, ggrind the damaged g pportion with ggrindingg wheel. 2. After that , mix the aerosol powder with hardener, this mixture has to be put on damaged portion, portion hardener is used to set quickly that joint. 3. Surface is very soft material, this has to put on that portion & paste with resin which is used for sticking & hardening.
4. Matt & robin are the strength of that lamination process these both used one by one on damaged portion. 5. The robin & matt used up to 7 times 6. Resin pour on robin & matt
1. After Completion of each section of pipeline, it shall be tested for water tightness before being covered in. in
2. This can be done by closing each end by means of valve, blank flange, cap or plug and filling the pipe with water.
3. The pressure shall be raised gradually by means of a hydro testing pump till the pressure is at least one and half times th working the ki pressure. 4. A pressure to be specified by the authority for a duration of one hour.
NOTE : In the test pressure drops after one hour